Polymerization of vinyl monomers in separated Winsor II (w/o) and Winsor I (o/w) microemulsion phases. Part 1: preparation and characterization of polymerizable vinyl-monomer-containing microemulsions

Abstract

Classical toluene-based (w/o, water in oil) single-phase Winsor IV inverse microemulsions containing toluene/(sodium bis(2-ethylhexyl) sulfosuccinate (AOT)/water/acrylamide (AAm)/sodium dodecyl sulphate (SDS) and containing, besides AAm, also an oil-soluble vinyl monomer (butyl acrylate (BA), styrene (S), or ethyl acrylate (EA)) were titrated by aqueous titrating systems (TS) composed from water (TA), aqueous solutions of acrylamide (TB), aqueous solutions of sodium dodecyl sulfate (TC), and/or aqueous solution of acrylamide and sodium dodecyl sulphate (TD). The amount of TS absorbed by the inverse microemulsion during titration (i.e., before transformation of Winsor IV inverse microemulsion to the two-phase Winsor II (w/o) (microemulsion phase + aqueous phase) and/or before phase inversion to the Winsor I (o/w) (microemulsion phase + oil phase) microemulsions, depended only slightly on the nature of the oil-soluble vinyl monomer. It was found, however, that the ratios of intra-phase and inter-phase compositional parameters such as toluene/AOT and AOT/SDS of the single-phase Winsor IV (w/o) inverse microemulsions considerably affected the value of the volume fractions of the aqueous phase, Φaw2, necessary for the formation of a two-phase Winsor II (w/o) and/or Winsor I (o/w) microemulsion systems. The composition of the titrating systems TS influenced the Φaw2 values at which the phase separation, and/or phase inversion of the single-phase Winsor IV (w/o) inverse microemulsion, were observed. Thus, the following sequence TAS1 < TA ≪ TC < TB < TD of titrating systems (ordered according to the obtained Φaw2 values) was found.